1. Field of the Invention
The invention relates to a technology for estimating the stress-strain behavior of various portions of a molded-component.
2. Description of the Related Art
The advent of computer aided engineering (CAE) has made it possible to execute computer simulations such as a crash analysis, a vibration analysis and a stress analysis at the stage of product design. As a result, the safety and durability of a product can be evaluated in advance. In such computer simulations, the shape and characteristic values of the product targeted for the analyses need to be presented in the forms of numeric models. Therefore, the degrees of accuracies of such numeric models have considerable influences on the analysis results.
Some components included in the product may be manufactured by casting (these components will be referred to as the “molded-components”). The stress-strain behavior of the molded-component is not entirely uniform, namely, the stress-strain behavior varies from portion to portion of the molded-component. Such variations occur due, mainly, to the variations in the solidification time among the portions during casting. Accordingly, the numeric models should be prepared with the stress-strain distribution in the molded-component taken into account in order to obtain accurate analysis results through CAE.
However, an actual molded-component may not be available at the stage of product design. Even if an actual molded-component is present, there may be some portions from which test pieces used for a tensile test cannot be cut out due to the shape of the molded-component. Accordingly, it is difficult to actually measure the stress-strain distribution in the entire molded-component. In addition, one product usually has several tens of thousands to several millions of portions, and, therefore, it is impractical to actually measure the stress-strain behavior of all these portions.
Japanese Patent No. 2871894 (Japanese Patent Application Publication No. 04-361849 (JP-A-04-361849)) and Japanese Patent Application Publication No. 2001-121242 (JP-A-2004-121242)) describe the method for optimizing, using a computer, a die used to form a molded-component and the condition under which casting is performed. Japanese Patent Application Publication No. 2004-174512 (JP-A-2004-174512) describes the method for analyzing, using a computer, a strain and a stress caused in a molded-component. However, the variations in the stress-strain behavior from portion to portion of a molded-component due to the variations in the solidification time are not taken into account in execution of these methods.